The present invention relates to an alternative energy source. More specifically, the present invention is a generator system for converting water wave power to electricity.
The world consumption of electricity in 2007 is estimated by the U.S. Energy Information Administration to be about 16.33 trillion kilowatt-hours (kWh). In the United States, the world's largest consumer of electricity, annual consumption is nearly 4 trillion kWh. Consumption is rapidly increasing world-wide. As demand increases, the cost of electricity also increases. Since 2000, the retail price for electricity has increased by between 2-4 percent per year.
Most electricity in the U.S. is generated using non-renewable resources, such as coal (52 percent of generation), nuclear (21 percent), and natural gas (16 percent). The use of renewable resources represents only about 8 percent of the electricity generation in the U.S., with hydroelectric power from rivers accounting for most of the generation.
The burning of fossil fuels such as coal to generate electricity is a major contributor to many environmental ills, such as greenhouse gas emissions, acid rain, and air pollution. Additionally, as fossil fuels are non-renewable, the depletion of the world's reserves of fossil fuels for electricity generation is believed to contribute significantly to the rapidly increasing cost of retail electricity. Therefore, there is increasing interest in developing alternative energy sources, such as wind, solar, and ocean wave technologies. It is estimated that harnessing less then 0.2 percent of the mechanical energy generated by ocean waves and currents could fulfill all of the world's electricity demand.
Many technologies have attempted to capture and harness the energy in ocean waves. Many of these technologies are based upon air turbine technologies, such as windmills. The size of windmills has slowed their adoption as an alternative energy generation technology, as the windmills are considered to be unsightly. However, as the density of water is approximately 1000 times that of air, the power conversion devices for water technologies have the potential to be more efficient and correspondingly more compact.
Some technologies utilize tethered buoys that rise and fall with the motion of the ocean waves at the surface. The up-and-down motion of the buoys is used to drive a generator, such as a turbine or electro-magnetic generator. Other technologies utilize no moving parts, but channel the waves into reservoirs to drive hydroelectric turbines or allow the passing waves to manipulate the pressure of air trapped in channels to drive turbines. Many conventional wave power extraction systems only work in relatively high waves, making the systems impractical for many areas with low or inconsistent wave heights. For example, most of the eastern seaboard in the U.S. would not be able to utilize these types of technologies.
Yet another known technology relies upon well-known water wheel systems. Long used in rivers to generate power, water wheels are covered in vanes that are partially submerged in a continuous current. The water driven by the current pushes against the flat planes of the vanes to turn the wheel. This force causes the wheel to turn. In slower rivers, the water is diverted to the top of the wheel so that the force of gravity may be added to the force from the current in turning the wheel.
Adapting water wheel technology to the oceans has proven difficult for a variety of reasons. First, the intermittent nature of ocean waves makes continuously turning a water wheel difficult to achieve. Second, the breaking of the ocean waves can swamp the water wheel, imparting force to vanes on all sides of the water wheel. No force imbalance is created, so the water wheel does not spin. Further, many of these technologies only work in relatively high waves, making the systems impractical for many areas with low or inconsistent wave heights. Finally, the directionality of the ocean waves change over time, sometimes even over the course of a day. Keeping the water wheel aligned with the oncoming waves is critical to efficient operation, but alignment can be difficult to achieve, especially in choppy seas.
Technologies exist that attempt to address these difficulties. For example, U.S. Pat. No. 4,296,602 to Hanes et al., incorporated herein by reference, discusses an elongated water wheel rotatably mounted to a support structure that includes a concrete foundation pad on the seabed. The perimeter of the water wheel includes a plurality of bucket-like vanes, with a portion of the vanes submerged. A ramp is disposed on the wave side of the wheel and extends from just beneath the surface to the top of the water wheel, essentially shielding the water wheel from the impact of the waves. A holding tank is provided at the top of the ramp and above the water wheel. As waves encounter the device, the waves impact the ramp so that the water is driven up the ramp and into the holding tank. The holding tank directs the water to the vanes of the water wheel, imparting a force on the vanes. The water wheel rotates in response to the force. Energy is extracted from the rotating wheel by a generator or similar device.
There remains a need in the art for a system that efficiently extracts energy from a wide range of ocean wave heights at low cost and without the need for significant and unsightly structures.